The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.
Mobile radio antenna is installed with more and more functions that can be remotely queried or remotely controlled. Known applications of this kind include, for example, a remote electrical tilt (RET) device for electronic down tilt angle adjustment, a remote azimuth steering (RAB) device, a remote azimuth beamwidth (RAB), and the like.
Such units could not be interconnected because each antenna manufacturer has a proprietary control system for its antenna, but recent LTE (Long Term Evolution) wireless or radio base stations, etc. are frequently adopting AISG (Antenna Interface Standards Group) or 3GPP (3rd Generation Partnership Project) standards for controlling antennas. The AISG standard is the specifications standardized for ensuring the interoperability of the antennas with respect to their tilting control schemes.
Usually, a wireless base station antenna and its controlling RET device or such AISG device (AISG functional unit: Antenna Line Device or ALD) are placed in a high position, such as the top of a tower and a building roof. On the other hand, a wireless device for supplying power to the antenna or a control device (AISG control device: primary) can commonly be disposed at a lower position such as the bottom of the tower. Here, the control device transmits a control signal (RS485 standard signal) to an AISG device, and executes the control of the antenna by controlling the AISG device while supplying power to the AISG device.
According to the 3GPP or AISG standards, RET control is largely classified by, for example, a primary station and the secondary station. A mobile communication base station may be typically configured by an antenna system installed at a high position of a building, pole, etc., a base station main system installed on the ground, and a feeder cable connecting between the two, wherein the primary station may correspond to the base station main system, and the secondary station to the antenna system.
In such antenna systems, the antenna control apparatus has its wireless device output an RF signal which is a feed signal for supplying power to the antenna, has its AISG control device output an AISG signal composed of a direct current power for driving AISG units and their control signal. Then, a BS (base station) modem combines a modulated signal obtained by modulating the RF signal and AISG signal, and transmits the combined signal via the feeder cable to an antenna modem of the antenna system. The antenna system causes the antenna modem to separate the combined signal into the modulated signal and the RF signal, supply the antenna with the RF signal power after the separation, and provide the AISG devices with an output of the AISG signal composed of a direct current power and a control signal obtained from demodulating the modulated signal by a modem circuit (demodulation circuit) within the antenna modem.